December 15

Common E-bike Battery Problems and How to Fix Them

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There’s nothing worse than having to spend hundreds or thousands on an eBike only to have problems with its battery. Don’t get me wrong; e-bike batteries are built to last - but they’re still prone to failure if they aren’t adequately taken care of during their lifetime. 

What happens if your battery fails? 

Well, in this article, I’ve covered some most common eBike battery problems and how to fix them. So, if you’d like to know more - keep scrolling!

Ebike Battery Problems

When it comes to eBike troubleshooting, there are a couple of things that might be causing your battery problems, including:

  • eBike battery pack swelling

  • eBike battery not charging

  • eBike battery not running for very long

  • eBike battery pack not holding a charge

  • eBike not turning on

  • eBike not speeding up

Don’t worry, though - I’ll walk you through each one here!

Ebike battery - public ebike

eBike Battery Pack Swelling

If your eBike battery pack is swelling up, well, you likely have a pretty serious problem with one - or more - of the lithium-ion cells. 

Some electric bike models use flat pack cells - and these are known to swell if they suffer some damage. On the other hand, the 18650 lithium-ion cells are far more resistant to swelling and, in turn, more reliable.

If you notice that your eBike’s battery pack has a bulge in it, be sure you turn off the power and carefully remove the battery from your eBike. It’s a good idea to recycle the battery; most cities have a place where you can do this.

Now, some eBike battery packs are positioned inside the bike’s frame. That makes it somewhat harder to notice if you have a swollen battery pack. 

The only way to check if the battery is swollen is to drop the lower plate and take out the battery pack. Note that you’ll have to disconnect some cables before you do this.

eBike Battery Not Charging

If your battery isn’t charging, start by checking the following:

  • Is the power turned on at the outlet?
  • Is the charger working and outputting over 36 Volts?
  • Is the battery hot?
  • Is the battery charger port full of dirt?
  • Has the battery been left discharged for several months?
  • Has the fuse blown in either the eBike battery pack or the charger?

eBike Battery Not Running For Very Long

Lithium-ion batteries generally have a life of 700 charge cycles. They usually tend to lose full charge capacity over this mark.

That is entirely normal - and will, unfortunately, only get worse as time goes on.

Still, if you’re charging your bike every few days, you should be able to get many years out of your electric bike before you begin to notice the capacity of your battery is starting to degrade.

If you notice your eBike battery isn’t running as long as it used to, check the following:

  • Is the battery pack being charged to 100%?
  • Do you have a dragging of a disc brake?
  • Is the terrain uphill?
  • Are you assisting your battery by peddling?
  • Are your eBike’s wheel bearings freely spinning?
  • Do you have a short circuit in the battery, wiring, or motor?

Any of the scenarios mentioned above could lead to your battery discharging rather quickly.


eBike Battery Pack Not Holding A Charge

Lithium-ion batteries are good at holding a charge. However, like any other type of battery, they will slowly discharge over time.

If your eBike hasn’t been charged for a more extended period, it would be a good idea to give it a top-up - and see how it goes.

If you notice that you’re charging your battery, but it still discharges quickly without being used, you might have a short circuit somewhere or a faulty battery at your hands.

Here’s a quick test that can detect the problem: 

Remove the battery pack from your eBike and charge it up on a bench. Once it’s fully charged, test the battery by leaving it off the bike.

If it holds a charge, the issue will be your electric bike - most likely a short circuit in the bike's wiring or the motor. However, if it doesn’t hold the charge, your lithium-ion cell is faulty.

How Do I Know If My Bike’s Battery Is Charged?

Your battery charger will probably feature a LED light indicator that changes states depending on the bike’s battery level. It’ll go from red to green when the battery is fully charged in most cases. 

However, in some chargers, the LED light will turn off completely when the battery is charged. 

Either way, the point remains the same - you’ll have a way to track the progress while charging the battery. 

Remember not to leave the battery pack on the charger longer than 24 hours, though. 

Lithium-ion batteries don’t prefer being left on the charger. In the short term, this won’t hurt - but after a while, the battery’s capacity will go down.

You’ll also have an indicator of the battery’s current level on the battery pack itself or the speed controller. Some will use a 0-100% range, while others have a series of LED lights, depending on the model.

eBike Not Turning On

eBike Not Turning On

Let’s start with the obvious solution: 

If your e-bike isn’t turning on, be sure to check if the main switch is in the “On” position. 

Next, check the fuse for the battery pack. This fuse is usually located on the side and could blow up because of short circuits, vibrations, over-current, or old age.

If the fuse is in good condition and the battery pack is fully charged, check if the speed controller is in good condition, as well. The speed controller is the component that sends signals to turn on the battery pack.

These speed controllers could malfunction if damaged - either by dropping your bike or allowing water to get into them.

Hold the bike's “On” button for about 10 seconds to force the speed controller to turn on. Some speed controllers are turned on by pressing the “M” button. Again, it depends on the e-bike model you have.

Be sure to check that your battery pack has at least two bars of power. An extremely low battery power level can lead to your electric bike not turning on, by the way.

Another thing to check here is that the electrical cables are correctly connected. Sometimes, the dirt roads can dislodge the cable connections; this is often the case with mountain electric bikes. 

Water can find its way into these connections, too. Pull them apart and ensure the connection is tight.

eBike Not Speeding Up

eBike Not Speeding Up

There are numerous reasons why your electric bike isn’t speeding up. 

More often than not, the feedback magnets - positioned on the pedal crank or the rear wheel hub - for the proximity switch get dirty. Clean them with a rag, and you should be good to go. 

This common eBike battery issue is often wrongly diagnosed.

Most quality electric bikes feature a switch on the back and front brakes to stop the drive motor. In some cases, these switches can get stuck - leading to their failure. Activate both brake levers a couple of times to try and free up the switch.

To check the limit switch, though, you might have to remove the whole rear or front brake lever. That’s another reason why you should avoid leaving your eBike out in the rain.

Also, while it might sound obvious, be sure to check if you’re in the proper mode - for example, pedal-assist, throttle-only, or pedal-only. I’ve sometimes found myself in the wrong mode, and I couldn’t figure out why my eBike isn’t speeding up.

There is typically a minimum speed that will activate the drive motor. That is just a safety feature - and it’s usually around 1.8 mph.

What Speed Are eBikes Limited To?

eBikes are limited to 25 km/h - or 15.5 mph - to conform to the majority of road rules around the globe. Once the motor reaches this speed limit, it will stop providing power further. 

Of course, you can still pedal faster than 25 km/h, but you won’t get any assistance from the main motor.

Once the speed controller recognizes that you’re under 25 km/h, the battery management system will again supply power to the main motor. That is a standard component on most electric bikes - and, again, its role is to ensure that you conform to road rules.

Is 250Watts Enough For An eBike?

In most standard cases of use, 250W is more than enough power for you to ride your eBike on asphalt or dirt roads casually. A 250W drive motor is usually limited to 15 mph and can handle up to 240 pounds in rider weight. 

If that doesn’t sound impressive, remember that you can always assist the main drive motor by pedaling. 

You can always upgrade your bike with a Bafang conversion kit, though!

Conclusion

We can agree that e-bikes have come a long way since their first appearance. Granted, battery problems can occasionally happen, but most can be solved easily and quickly. 

Hopefully, the tips I’ve outlined above will help you keep your eBike running fast - and for a long time. And remember: 

The most significant danger to batteries of eBikes is excessive heat and low voltage. Make sure you keep your eBike battery topped up - and it will last for a very long time.

About the author

Emma was born and raised in the UK, studied in Amsterdam (where she discovered her passion for biking), and is currently living in Ohio. Her main passion is cycling, that's why she is always looking for an amazing new e-bike to make her journey even more unforgettable!


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  1. Hi
    I just bought a new e bike
    First time i have used it all was fine
    When i wanna charge it for 1st time there has been no charge sept by the battery.
    The charger la good but the battery don t keep charge
    The fuses(2) are good and electricity crosses the battery but don t keep charge.
    The company replaced the battery without see it but i liked To know if it s something To do with that problem
    Best regards

  2. My ebike will cut out. I then have to remove the battery and then put it back in. The bike will run ok for a minute or two but cuts out again. I remove the battery and put it back in. It cuts out again after a minute or so. The battery still shows 2-3 bars full. Is my 4 year old battery bad, or is it some other component?

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